As a result of the development of low-voltage technology, a multi-component electronic system may operate in a mixed mode, i.e., some components operating at a voltage level of 3.3V and some components operating at a voltage level of 5V. Conversion between the two voltage levels is often necessary to prevent damage to the 3.3V components. In view of the above, it is desirable to develop a voltage clamping mechanism to protect the 3.3V components from being exposed to high voltage.